Apparatus for recovering ammonia.



A. B. DUFF.

APPARATUS FOR REOOVERING AMMONIA. APPLICATION FILED NIB. 9, 1910.

1,003,887, Patented Sept. 19, 1911.

WITNESSES INVENTOR AL-gm plant consun'iing UNITED TESPAT NT OFFICE.

ALFRED BARKER DUFF, OF PITTSBURG, PENNSYLVANIA.

APPARATUS FOR RECOVERING AMMONIA.

To all whom it may concern:

Be it known that I, An'rnno BARKER Dori, a subject of the King of Great llritain and Ireland, and a resident of littsburg, lennsyl'vania United States of America, have invented certain new and useful Improvements in Apparatus for the Recovery o'l Ammonia from Gas-Producer Gas, of which the following the specification.

This invention has for its object to improve the process and simplitv the apparatus used in the recovery of ammonia 'lrom gas producer gas.

As is known, the ordinary process for the production of ammonia hy the eomljnistion of coal in a gas producer in the'presence of steam requires the introduction into the producer of a volume of steam largely in excess of that required for the conversion of the nitrogen of the coal into ammonia, in order to prevent the decomposition of the ammonia by heat. Further in the ordinary recovery plant steam is also required to boil down the weak sulfate of ammonia produced by treating the gas with a weak sulfuric acid solution. The large volume of steam thus required is usually raised in separate boiler a large amount of addi tional fuel to that gasitied. The expenditnre for this additional fuel therefore ren ders the process wasteful and uneeonomical to that extent. The temperature of the gas leaving the producer is considerable, and according to the present invention by the provision of an im iiroved construction and arrangement"ot plant, the sensible heat. of the gas issuing from the producer is first at ilized for the boiling down of the weak sullate liquor and second for the produetiim of the steam, or nearly all of the steam, and for the heating of the air required in the producer before the gas passes to the ammonia recovery tower. By this particular sequence of operations and plant not only is economy in Working effected but the recovtmy plant is also-lessened and the process shortt-eued.

A simple example of the improved construction oil. plant is shown in elevation partly in section on an accompanying sheet of explanatory drawings.

As shown in the drawings the gas pro (lueers oi. which only one A is shown, are fed with .fuel as usual each by a central hopper A charged when required from an overhead hopper A to which the fuel is 'aised by the usual elevator A, The gas Specification of Letters Patent. Application filed February 9. 1910.

Patented Sept. 19, 1911. Serial No. 542,849.

generated, on leaving each producer passes by a pipe B into the usual colleetingalnd dust separating main B". From the main the gas is led by a pipe 1'3 to the interior of a casing (l surroumling a boiling down pan (1. This pan is of usual mnstruetion, that is, it is titled with an overhead vapor collecting canopy (l and vapor discharge pipe C and a valve controlled outlet C through which the crystals and liquor formed are discharged to a drainer l), heneath which is the usual liquor well D. A valve controlled pipe D leads from the pipe I) by means of which circulation is kept'np in the ammonia recovery tower l), as hereinafter. described, so that the weak sulit'ate liquor may pass when required by the pipe I) to the boiling down pan (l Only a small amount of the heat in the gas within the casing (,3 is required to expeditiously boil down this liquor, so that the leaves this easing still having a considerable portion of its sensible heat. From the casing C the gas passes by a pipe connection E" to and enters the bottom of a gas washing and heat exchanging tower E this tower being filled vi'iroducei'l in that tower in the usual nn'inner, i

with batten ehcclierwork R or the like.

Water is admitted, as hereilxafter described, I to the top of this tower and falls tin-(nigh it so that the water is brought into intin'iate contact with the gases ascending theres through, and as the heat: in the gas is ample for the purpose, the trnnpcraturo of the water is raised to or near boiling point. at the same time the water washes out the dust and a portion ol' the tars which the gas held in a fluid comlition. On reaching the bottom of the tower, the water and tars Fall into a tank li luting the bottom of the tower, and the water is drawn from this tank by a centrifugal pump l and forced up a pipe (l to the top of a second tower (i placed above the gas washing tower, the water entering this tower through a spray device It in its upper end, and leaving the. bottom thereof through a pipe connection (i eommunicating through a spray device R with the interior of the lower tower l? at the top oil the latter. The upper tower is also filled with batten checlccrwork h or the like. Air from a hlower llt enters the bottom of the upper tower (l through a pipe H. and as the air and the boiling water pass through this upper tower in opposite directions, not only is the air highly heated but all, or a very large amount of, the steam required in the producer passes oif from the.

tower with this heated air through the pipe connections H The end of these pipe connections next the producer is fitted with a regulating valve H and enters what may be termed a false top, or inclo-sed space H formed in the top of the producer, so that advantage may thus be taken of the great heat at that part of the producer to superheat the mixture of air and steam. From this inclosedspace H 1 the air and steam is led bya pipe J communicating as usual with the interior of the producer.

As hereinbefore described, the water after parting with most of its heat and steam to the air passing through the upper tower G passes by the pipe connection G into the gas washing tower E and is there re-heated to or near the boiling point and again forced by the pump L through the pipe G .to the upper end of the upper tower G the circulation thus being continuous. Vhen the gas leaves the washing tower E its temperature is then suiiiciently reduced to permit of it being treated in the ordinary ammonia recovery tower, and from the gas washing tower E the gas passes by pipe connections J to the bottom of the ammonia recovery tower E where it is treated as usual with a weak sulfuric acid solution to produce the weak sulfate of ammonia, the solution being kept in circulation by a centrifugal pump N drawing the liquid from the usual acid tank J and forcing it by the pipe D to the top of the ammonia recovery tower E.

From this tower the gas passes through the usual main K either direct to a receiver or through mechanical washing plant of any desired form, depending on the use to which it is to be put.

WVhat I claim is 1. In apparatus for the recovery of ammonia from gas producer gas, the combination in the following sequence of a gas producer, a liquid concentrating device for boiling down the weak solution of ammonium' sulfate, means for raising at least some of the steam and for heating the air required in the gas producer, and an ammonia re covery tower in which the cooledgas is treated as usual. v

2. In apparatus for the recovery of ammonia from gas producer gas, the combina tion in the following sequence of a gas producer, a liquid concentrating device for boiling down the weak solution of ammonium sulfate, a heat interchanger in which water is heated to or near the boiling point, and an'ammonia' recovery tower in which the cooled gas is treated as usual, together with a secondheat interchanger connected to said first heat interchanger, means for producing therein the mixture of air and steam required in the gas producer, and means for leading said mixture of air and steam to the gas producer.

3. In apparatus for the recovery of ammonia from gas producer gas, the combination in the following sequence of a gas pro ducer, a liquid concentrating device for h'oil ing down the weak solution of ammonium sulfate, a heat interchanger in which water is heated to or near the boiling point, and an ammonia. recovery tower in which the cooled gas is treated as usual, together with a second heat interchanger connected to said first heat interchanger, means for pro ducing therein the mixture of air and steam required in the gas producer a superheater and means for leading-the mixture of air and steam through said superheater to the gas producer.

4. In apparatus for the recovery of ammonia from gas producer gas, the combination in the following sequence of a gas producer, a liquid concentrating device for boiling down the weak solution of ammonium sulfate, a heat interchanger in which water is heated to or near the boiling point, and an ammonia recovery tower in which the cooled gas is treated as usual, together with a second heat interchanger arranged above said first heat interchanger, means for leading the heated water from the lower to the top of the upper heat interchanger, means for leading up through said second heat interchanger a counter-current of air wherebya mixture of air and steam is secured and means for leading this mixture to the gas producer.

6. In apparatus for the recovery of ammonia from gas producer gas, the combination in the following sequence of a gas producer, a liquid concentrating device for boiling down the weak solution of ammonium sulfate, a heat interchanger 'in which water is heated to or near the boiling point, and an ammonia recovery tower in which the cooled gas is treated as usual, together with a second heat interchanger arranged above said first heat interchanger, means for leading the heated water from the lower to the top of the upper heat interchanger, means for leading up through said second heat interchanger a counter-current of air whereby a mixture of air and steam is secured, means for leading the cooled water from the upper to the lower heat interchanger to wash the gas therein so that the circulation is continuous, and means for leading the mixture of air and steam from the upper heat interchanger to the gas producer.

'6. In apparatus for the recovery of ammonia from gas producer gas, the combination in the following sequence of a gas producer, a liquid concentrating device for boiling down the weak solution ofammonium sulfate, a heat interchanger in which water is heated to or near the bolhng point, and

an ammonia recovery tower in which the cooled gas is treated a second heat interchanger arranged above said first heat inter-changer, means for leading the heated water from the lower to the top of the upper heat interchanger, means for leading up through said second heat interchanger a counter-current of air whereby a mixture. of air and steam is secured, a superheater and means for leading the mixture of air and steam from the upper heat said superheater to In apparatus for the recovery of ammonia from gas producer gas, the combination in the following sequence of a gas proas usual, together with ducer, a liquid concentrating device to which the weak solution of ammonium sulfate is led from the recovery tower, a heat interchanger in which at least part of the steam 20 required for the gas producer is raised, and an ammonia recovery tower to which is led the gas cooled in the heat interchanging tower.

In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses.

ALFRED BARKER DUFF.

WVitnesses JAMES BURNS, Ronnn'r. HENRY HILL. 

